Communication systems employing signal diversity reception are known. In one example, remote receive sites are located throughout the coverage area of a communication system in order to improve signal reception from low powered communication devices. Each remote site that contemporaneously receives a version of a common source signal transmitted from a communication device, transfers the received signals to a common location, or central site, where these signals are used to derive an output signal representing the originally transmitted source signal. Generally, in an analog communication system, a voter compares the signal quality for the signals received from the various remote receive sites and selects the site which has the best signal quality as the preferred source for the originally transmitted signal.
The use of digital transmissions presents additional opportunities over that of analog transmissions for providing an enhanced signal reception system. The original digital message can be derived from more sophisticated analysis of the various messages available at the remote receive sites. For example, error detection coding may be included in each message received at a remote receive site. The central site then chooses from among the messages received at the various remote sites to minimize the potential of error. In another example, remote receive sites, which receive signals with a signal quality above some predetermined threshold, transfer the signal, in the form of a data symbol stream, back to a common location. The data symbols are then time aligned, if necessary, and voted on symbol by symbol. Generally, the output data symbol stream contains the most frequently occurring symbols from all the receive sites. When the number of receive sites is even, other approaches are needed to choose the proper data symbols within the received data symbol stream.
It is desirable to improve the likelihood of recovering an original transmitted source signal by employing geographically separated remote receive sites. The signal quality of each version of a signal received at each remote receive site may be affected by a variety of factors. Preferably, a substantial portion of the available signal quality information is used to recover the transmitted signal. A method in which the original source signal is determined based on a simple numerical preponderance of particular data symbols from the various remote sites is not sufficient. Therefore, a new signal diversity reception scheme is needed that better utilizes available information to recover an original source signal.